20 pack doesnt work..... :(

I had bought a 20 pack of Digital OPKs from Rite aid last month to prepare for this month....they last box of 7 were good and worked daily. HOWEVER, this expensive box thus far has only had 2 work. So far 7 have read error or nothing at all. Its frustrating enough having infertility problems and then to haves test that don't work. Super aggravated and let down for all I paid for the big box.